Study Of Ofdm/ofdma Sychronization Technique In The Physical Layer Of Wimax

WiMAX is a new broadband wireless access technology which is the best method of last-mile access,and satisfies user's need of mobiling, bandwiding in wireless communication. WiMAX standard includes IEEE802.16d and IEEE802.16e. IEEE802.16d supports fixed access while IEEE802.16e supports both fixed access and mobile access. There are four frameworks available in WiMAX physical layer: WirelessMAN-SCa, WirelessMAN-OFDM, WirelessMAN-OFDMA , WirelessMAN-HUMAN.In this paper, the WirelessMAN-OFDM and WirelessMAN-OFDMA framework is studied combined with the IEEE 802.16d/e standard. The author goes deep into the OFDM/OFDMA technique.The synchronization principle of carrier,sampling and symbol and their effect to the OFDM system are analized while providing emulation results.Algorithms and emulations are provided according to each kind of synchronization.The completed synchronization process of OFDM system in WIMAX's physiccal layer is provided.The estimation algorithms about parameters induding Fine Timing Synchronization Algorithm,Joint Estimation of Fraction-frequency and Timing Algorithm,Integer-frequency Estimation Algorithm and Tracking Phase Based Pilot Agorithm are provided. Also,the author gives the emulation of the algorithms,and gets a good result. The author goes deep into the synchronization of OFDMA up-link frequency offset and its compensation method.Then, Multi-User Frequecy Offset Estimation Algorithm Based Sub-space Structure is provided ,and also with its emulation result which shows its better performance than the ML algorithm.Last,the author simply analyzes the uplink-ranging technology which provides basement for the future research.